This Research Conference will focus on the molecular mechanisms of smooth muscle proliferation and cystic lung destruction that occur in lymphangioleiomyomatosis (LAM). This is the fourth annual conference on the topic, which has evolved from a dedicated family/patient conference to include state of the art basic and clinical science meetings on LAM by expert investigators. The basic science sessions will highlight research on research on the cellular and genetic basis of smooth muscle proliferation in LAM, and will focus on the role of exogenous growth factors, sex hormones, gene mutations, intracellular signaling mechanisms and changes in transcription regulation in LAM. Additional sessions will explore the link between smooth muscle infiltration of the lung and the cystic remodeling of the pulmonary parenchyma, including the elaboration of metalloproteinases and connective tissue matrix by LAM cells. Concurrent clinical sessions will explore difficult management issues in LAM including hormone therapy, air travel, pregnancy, lung transplantation and pleural complications. The clinical and basic science tracks have been coordinated to allow all participants to attend keynote sessions and to traffic freely between sessions. A patient oriented seminar will address key issues for 70 LAM families who are expected to attend, and will culminate in a summary of the clinical and basic science sessions and a roundtable discussion on the last day of the conference. Each session will be chaired by an expert in the field and will have invited speakers chosen from the pool of submitted abstracts. There has been a conscious effort to attract established investigators from related disciplines who can complement the expertise of the current pool of LAM investigators. Discussion facilitated by a discussion leader will be an important component of all sessions. Outstanding junior investigators will be given the opportunity to present their research. It is hoped that creative and innovative new research directions advancing the understanding and treatment of LAM will emerge from this conference.